Balancing device for rotating members

ABSTRACT

A device for balancing rotating members positioned on a rotatable shaft or spindle. A pair of movable balance weights are positioned within the shaft or spindle and are movable both with respect to each other and in unison about the axis of rotation of the rotating mass. The device includes means for moving the balance weights while the structure within which they are housed is rotating.

United States atent Decker 1451 Nov. 7, 1972 [54] BALANCING DEVICE FORROTATING MEMBERS [72] Inventor: Jacob Decker, Cincinnati, Ohio [73]Assignee: Cincinnati Milacron Inc., Cincinnati, Ohio [22] Filed: Nov.13, 1969 [211 Appl. No.: 876,308

52] us. c1 "174/573, 51/169 51 1111. c1. ..Fl6f 15/00 [58] Field ofSearch ..74/573; 51/169 [56] References Cited UNITED STATES PATENTS2,241,637 5/1941 Ernst et al ..51/169 x FOREIGN PATENTS OR APPLICATIONS1,106,901 3/l968 Great Britain ..5 1/169 Primary Examiner-William F.ODea Assistant Examiner-F. D. Shoemaker Attorneyl-Ioward T. Keiser andAlfred J. Mangels [5 7 ABSTRACT A device for balancing rotating memberspositioned on a rotatable shaft or spindle. A pair of movable balanceweights are positioned within the shaft or spindle and are movable bothwith respect to each other and in unison about the axis of rotation ofthe rotating mass. The device includes means for moving the balanceweights while the structure within which they are housed is rotating. 1

10 Claims, 7 Drawing Figures 'PATENTEDNB 1 m2 3102.082 SHEET 1 BF 3 BYNEYS PATENTEDNHY 11912 I 3.702.082

SHEET 2 OF .3

BACKGROUND OF THE INVENTION This invention relates to a device forbalancing rotating masses. More particularly, the invention relates to abalancing device wherein a pair of balance weights positioned withinarotating shaft or spindle are movable relative to the rotating shaft andrelative to each other to bring the rotating mass into rotationalbalance.

In the field of rotating machinery the need for keeping the rotatingelements in balance is well-known to those skilled in the art. Theeffects of unbalance can include: excessive bearing wear, excessivenoise, and, in the case of metalworking machinery, unbalance can resultin vibrations which contribute to non-uniform and unacceptable surfacefinishes.

To overcome those problems and provide means for balancing rotatingmembers, numerous devices have been proposed. MOst of the proposeddevices have contemplated automatically sensing unbalance andcompensating for it'by moving balance weights to the required positionto bring the rotating mass into rotational balance once again. Suchautomatic devices are generally quite complex from a mechanicalstandpoint, and thus are costly items which can usually only bejustified on very' expensivemachinery. Therefore, a balancing devicewhich is relatively'simple, which can be manually operated, which can beeconomically produced, and which can provide the balancing functionnecessary is highly desirable.

Additionally, some balancing systems utilize a number of weights such assteel balls, which are released when unbalance is detected and whichbalance the systems by virtue of centrifugal forces acting on theweights to reposition them and thereby bring the rotating system intorotational equilibrium. However, the foregoing approach to balancingrequires that the rotating system be relatively loosely supported duringthe balancing operation rather than rigidly supported and thus thespindle-bearing assembly is unclamped so that the steel balls can assumea position that offsets the unbalance in the system. After balancing,the assembly is clamped once again so that the balls are firmly held inthe position they assumed to balance the system.

It is an object of the present invention to provide a relativelyinexpensive yet effective balancing device which, although generallyintended for manual operation, can be adapted for automatic operation ifdesired.

SUMMARY OF THE INVENTION Briefly stated, in accordance with one aspectof the present invention, a balancing device is provided for use withrotating members which can be positioned on a rotatable shaft orspindle. The device is adapted to balance the rotating member while thesame is rotating to thereby provide a quick and accurate means forbalancing such a rotating member. The device includes a pair of movablebalance weights positioned within the shaft or spindle so that each ofthe weights has its center of gravity radially spaced from the axis ofrotation of the shaft or spindle. Means are provided for moving thebalance weights relative to each other about the axis of rotation andalso for moving of the weights in unison about the axis of rotation. Therelative and unison motions of the balance weights are independentlycontrollable to provide accurate means for balancing the rotatingmember.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary perspectiveview of a portion of a grinding machine incorporating the deviceeonstituting the present invention.

.FIG. 2 is a longitudinal cross section through the spindle of thegrinding machine of FIG. 1, with a portion of the spindle broken away,showing the arrangement of the spindle driving means and the positioningand overall structure of the balancing device.

FIG. 3 is a fragmentary perspective view, partially in section, of theportion of the spindle within which the balancing device of the presentinvention is housed.

FIG. 4 is a cross-sectional view of the spindle taken along the line 4-4of FIG. 3 and shows a portion of the gear train system for moving thebalance weights.

FIG. 5 is a cross-sectional view of the spindle taken along the line 5-5of FIG. 3 and shows the driving means for moving one of the balanceweights.

FIG. 6 is fragmentary view, partially in section, showing the spindledrive means and the system for initiating and maintaining the movementof the balance weights.

FIG. 7 is a schematic diagram showing one means for actuating thebalance weight moving system and for locking the balance weights inposition after the rotating mass has been balanced.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings,and particularly to FIG. 1 thereof, there is shown a grinding machine 9comprising a base 10 upon which a spindle support 11 is slidablymounted. Spindle support 11, rotatably carries spindle 12 upon which agrinding wheel 13 is mounted. Spindle 12 is rotated by means of a motor(not shown) which drives the spindle through a pulley 14 by means ofV-belts 15. A wheel guard 16 is positioned over a portion of grindingwheel 13 for safety purposes. Additionally, a vibration amplitudeindicating device 17 can be attached to spindle support 11 to provide adirect visual indication of the amplitude of the vibrations and therebyfacilitate the balancing operation. Although herein described in termsof its applications to a grinding wheel forming a part of a grindingmachine, in which application the device of the present invention hasbeen found to be particularly suitable, it should be understood that thebalancing device comprising the present invention is not limited in itsapplication to grinding machines but can, if desired, be utilized inother rotating apparatus wherein a balancing device is either necessaryor desirable.

As shown more clearly in FIG. 2, grinding wheel 13 is positioned on anannular, flanged wheel-carrying member 18 and is firmly positionedthereon by means of a retaining disc 19 which can be secured to thewheel mount as, for example, by means of bolts 20. Wheelcarrying member18 is attached to spindle 12 in overlying concentric relationship to ahub portion 21, which connection can be made by means of bolts 22, forexample. Pulley 14 is affixed to spindle 12 at the end of the spindleopposite hub portion 21 as for example, by means of bolts 23.

Hub prtion21 of spindle 12 constitutes the housing for a pair of movableweights 24, 25, respectively, by means of which grinding wheel 13 andits associated rotating supporting members are brought into balance.Weights 24, 25 are similarly configured and, as shown in FIG. 3, theycomprise a generally. annular structure having outer surfaces 26, 27which can be rotated within hub portion 21, and inner surfaces 28, 29which carry internal gears 30, 31, respectively,the function of whichwill be hereinafter explainedin greater detail. 1

A portion of the material of which weights 24, 25 are made is removed onone side thereof to provide an unbalance in the weight. The unbalance isnecessary in order vto permit theweights to function as counter weightsand thus off-set any unb'alance in the rotating mass.1 In theconfiguration shown, arc-like slots 32, 33 have been" formed in weights24, 25, respectively and extend through *approximately 180 arc.Additionally, radial slots 34, 35 have been formed in the same portionsin which the arc-like slots 32,33, respectively were formed in order tofurther reduce the mass on one side of the balance weightsQIf desired,additionalarclike slots 36, 37 can be formed in balance weights 24,v

' present invention.

Referring once again to FIG. 2, weights 24, 25 are positioned withinhub21 in such a fashion that they can be readily rotated therein relativeto the inner surface of the hub to cause the hub to become unbalanced.Weight 25 is positioned against a stop 38 and weight 24 is positionedadjacent weight 25 and is held in position by means of a retaining ring39. A cover 40 can then be applied to hub 21, if desired, and securedthereto as, for example, by means of bolts 41. As previously mentioned,each of weights 24, 25 carries internal gears 30, 31, respectively.Th'ose gears are adapted to be driven by a gear train connected to meansto move the weights relative to one another or in unison relative to theaxis of rotation.

A hollow drive shaft 42 is co-axially and rotatably positioned withinspindle 12 and extends into hub 21 in which weights 24, 25 arepositioned. Shaft 42 carries a gear retainer. 43 which can be keyedthereto. as by means of the key 44 shown in FIG. 2. Attached to gearretainer 43 as, for example, by means of bolts 45 is a bearing retainer46 which includes a circular recess 47 to receive a thrust bearing 48.Positioned within hollow shaft 42 and rotatable with respect thereto isa'solid Referring now to FIG. 3, pinion 51 mates with an idler gear 53which, in turn, meshes with internal gear on weight 24. Thus, byrotating solid shaft 49, and thus pinion 51 attached thereto, weight 24is caused to rotate within hub portion 21. Idler gear 53 is mounted on ashaft 54 which passes through bearing'retainer 46 and which fixedlycarries at its opposite end a gear 55 which meshes with and drivesanother gear 56, which is mounted on a shaft 57 carried in gear retainer43 and to which is attached a driving gear 58, which meshes with anddrives internal gear 31 formed on the innermost surface of weight 25.

The arrangement of the gear train hereinabove described is shown moreclearly in'FIGS. 4 and 5. FIG. 4'is a transverse cross section takenthrough the gears 55, 56 and showing the relationship of those gearswith bearing retainer 46. Similarly, FIG. 5 is a transverse crosssection through driving gear 58 showing its relationship, with gearretainer 43 and internal gear 31. Although shown and described in termsof a gear train comprising five gears, it would be apparent to thoseskilled in the art that various other gearing arrangements could beemployed to provide similar results. For example, idler gear 53 and gear55 could be replaced by a single gear having a width 'which equals thedistance between the outermost faces of those gears. Similarly, withrespect to gear 56 and driving gear 58, a

similar elongated gear having a width substantially drive shaft 49,which also extends into hub 21 in which weights 24, 25 are housed. Solidshaft 49 has an end portion 50 of reduced cross-section which passesequal to the distance between the outermost faces of the gears 56 and 58could also be employed.

It can thus be seen that by rotating solid shaft 49 pinion 51 engagesidler gear 53 which, in turn, causes the weight 24 to rotate within hub21. Similarly, gear 55, attached to shaft 54 on which idler gear 53 iscarried, drives gear 56 which, in turn, rotates-shaft 57 on whichdriving gear 58,is positioned. The latter meshes with and drivesinternalgear 31 on the weight 25 Thus, by rotating solid shaft 49, weights 24,25 are caused to rotate about the axis. of rotation of spindle, l2 andsimultaneously to move relative to each other. On the other hand, whenhollow shaft 42 is rotated, the gear train is in a locked condition and,as a result, weights 24, 25 rotate in unison about the axis of rotationof spindle 12. I

Referring once again to FIG. 2, hollow shaft 42 carries a clutch member59, as by means of a key 60. Clutch member 59 has a-pressure face 61 andis held in position by a retaining ring 62 at its outermost end. Therear face of clutch member 59 abuts the outer race of thrust bearing 63,which is adapted to absorb the axial thrust imposed upon hollow shaft 42when clutch member 59 is driven.

' Solid drive shaft 49 also carries a clutch member 64 afiixed to itsoutermost end and secured for rotation with shaft 49 by means of a key65. Clutch member 64 is axially positioned on solid shaft 49 between end66 of hollow drive shaft 42 and nut 67 applied to threaded portion 68 ofsolid drive shaft 49. Each of clutch members 59, 64 has a generallyfrusto-conical pressure face 61, 70, respectively, which are oppositelypositioned.

Clutch members 59, 64 are housed within a cylindri cal recess 71 inpulley 14 within which an annular driving member 72 is also positioned.Annular driving member 72 has a V-shaped central portion 73 formed byoblique pressure faces 74, 75 respectively, and is adapted to bepositioned intermediate the clutch members 59, 64. Pressure faces 74, 75are opposite frustoconical clutch member pressure faces 61, 70,respectively. In one direction the axial movement of annular drivingmember 72 is restrained by the inner face 76 of pulley 14 and in theother direction by means of an annular restraining ring 77, which isattached to pulley 14 by means of bolts 78. Annular driving member 72 isboth rotatable about the axis of rotation of spindle 12 and is axiallytranslatable therealong a limited distance. It can thus be seen thatwhen annular driving member 72 is axially translated with respect tospindle 12, it can contact either of pressure faces 61, 70' of clutchmembers 59, 64, respectively. I

Axial movement of annular driving member 72 is imparted through a lever79 which is pinned by means of pin 80 to a supporting shaft 81journalled within a pair of bearings 82, 83 that are carried by abearing housing 84 which, in turn, is secured to annular driving member72 by means of annular end rings 85, 86 and bolts 87. Thus, when lever79 is caused to move outwardly, or to the right as viewed in FIG. 2, andannular driving member 72 is rotated in a manner to be hereinafterexplained, pressure face 75 of annular driving member 72 contacts andthus rotates pressure face 70 of clutch member 64 keyed to solid shaft49 which, in turn, drives the gear train and causes the weights to moverelative to each other. Conversely, when lever 79 moves inwardly or tothe left as viewed in FIG. 2, pressure face 74 of annular driving member72 contacts pressure face 61 of clutch member 59 keyed to hollow shaft42 and, because of the inter-connectionbetween the gears, ashereinbefore pointed out, the two weights move in unison about the axisof rotation of spindle 12.

As best seen in FIGS. 2 and 6, annular driving member 72 is driventhrough a positive drive system, such as, for example, a timing belt andtoothed pulley. A toothed pulley 88 is provided at one end of pulley 14adjacent to spindle 12 and by means of a timing belt 89 drives a dualpulley 90 (FIG. 6) having two toothed grooves 91, 92, and which isrotatably supported on a shaft 93 by means of bearings 94, 95. A timingbelt 96 passes around groove 92 also passes around a toothed pulley 97,which is attached to bearing housing 84 and thereby causes the latterand thus annular driving member 72 to be rotated. Depending upon thesizes of the various pulleys and grooves 88, 91, 92 and 97, annulardriving member 72 can be arranged to rotate at any desired speed.Preferably, however, those pulleys and grooves are so configured thatannular driving member 72 rotates at a speed slightly greater than orslightly less than that of spindle 12. When the speed difference betweenannular driving member 72 and spindle 12 is kept small, the relativerotation between the spindle and weights will also be kept small andthus will permit more precise correction of unbalance by more accuratelypositioning the balancing weights both with respect to each other andwith respect to spindle 12. The greater the speed differential betweenthe too elements, the more quickly will the balance weights reach anequlibrium position, but, in addition, there is a greater liklihood ofovershooting the balance point in that weights may not be stopped intheir movement until after the balance point has been reached.

As is apparent from the foregoing, annular driving member 72, and thusalso lever 79 have essentially three positions: an intermediate, orneutral position, and a right and left position, depending upon which ofshafts 42, 49, is to be driven. Although lever 79 can be moved manuallyif desired, a preferred embodiment of the present invention includeshydraulic means for positioning annular driving member 72. As best seenin FIG. 6, a three-position valve 98 is secured to a plate 99 affixed togrinding machine 9 and is so arranged that in its neutral position lever79 so positions annular driving member 72 that the latter also is in itsneutral position. The distances from pin to a fulcrum 100 tothreeposition valve 98 are so selectedthat when valve 98 is in oneextreme of its path of travel annular driving member 72 engages one ofthe clutch elements and when the valve is at the other extreme end ofits path of travel annular driving member 72 contacts the other clutchelement.

A suitable hydraulic system for positioning annular driving member 72 isshown in FIG. 7. A pump 101 is utilized to feed hydraulic oil through athree-position, four-connection directional valve 102 operated bysolonoids actuated by pushbuttons (not shown). When directional valve102 is at a neutral position, hydraulic pressure is applied to each endof three-position valve 98 and the latter is thus also in a neutralposition. When directional valve 102 is in one position, valve 98 causesthe lever to move in one direction and then directional valve 102 is inthe opposite extreme position the threeposition valve also reversesitself and causes the lever to move in'the opposite direction, therebycontrolling the direction and amount of rotation of the balance weights.

Also forming a portion of the hydraulic circuit illustrated in FIG. '7is a locking means for locking the balance weights in position after therotating mass has been balanced. The system comprises directional valve103 connected in parallel with valve 98 and which permits flow to aplurality of locking pistons 104 which bear against the outer face ofweight 25 (see also FIG. 2). The system is so arranged that whenthree-position valve 98 which actuates lever 79, which, in turn,controls annular driving member 72, is in the neutral position,directional valve 103 is also in the neutral position, therebypermitting hydraulic pressure to bear against the locking pistons 104which contact weight 25 and by virtue of the cooperation between lockingpistons 104 and retaining ring 39, the weights are retained in anydesired position relative to each other and also relative to hub 21.However, when three-position valve 98 is moved to either extreme of itspath of travel to actuate lever 79, and thereby engage one of clutchmembers 59, 64, directional valve 104 is also moved to one side or theother thereby releasing the the pressure on the locking piston andpermitting the balance weights to rotate.

Although described in terms of a mechanical drive system comprisingvarious frictional clutches and pulleys, it would be apparent to oneskilled in the art that other driving means can be utilized and stillprovide the benefits of this invention. For example, the mechanicalclutches can be replaced by electrical clutches and the hydraulicactuation system replaced by a suitable electrical system, if desired.

Itcan thus be seen that the present invention provides a compact,self-contained balancing device which is capable of either completelymanual operation or which can behydraulically actuated at the signal ofa machine operator. It is also apparent that the device disclosed inthepresent application is alsosuseptible of automatic control provided anelement for sensing unbalance and suitable automatic control functionsare incorporated therein. I

While particular embodiments of the invention have been illustrated anddescribed, it will be apparent to those skilled in the'art that variouschanges and modifications can be made without departing from the spiritand scope of the invention, and it is intended to cover in the appendedclaims all such changes and modifications that are within the scope ofthis invention.

What is claimed is:

1. A balancing device for balancing a rotating member positioned on arotatable spindle while the same is rotating about its axis of rotation,said device comprising: i

a. a pair of movable balance weights positioned within said spindle,said weights having their respective centers of gravity radially spacedfrom the axis of rotation of said spindle and axially spaced from eachother, each of said movable weights being of generally annularconfiguration and having internal gear teeth on its innermost sur-'face;

b. first weight-moving means for moving said balance weights relative toeach other and about said axis of rotation;

0. second weight moving means for moving said balance weights in unisonabout said spindle axis;

and

d. means for selectively engaging said first or said second weightmoving means whereby substantially to bring said rotating mass intobalance.

2..The device of claim 1 wherein said first weight moving means and saidsecond weight moving means comprise gear means meshing with saidinternal gear teeth to cause said balance weights to move relative toeach other whensaid first weight moving means is activated and to causesaid balance weights to move in unison about said axis of rotation whensaid second weight moving means is activated.

3. The device of claim 2 wherein said first weight moving means and saidsecond weight moving means are independently driven by separate clutchmeans connected to said gear means.

4. The device of claim 3 including power input means for selectivelyimparting rotational motion to each of said clutch means to thereby movesaid balance weights and. substantially balance said rotating member. I5. The device of claim 4 wherein said power input means comprises aclutch driving member driven by said spindle at a predetermined speeddifferent from that 'of said spindle, said clutch driving member beingselectively engageable with each of said clutch means.

6. The device of claim 5 including means for locking said movableweights in any desired position relative to said spindle.

7. The device of claim 6 wherein said locking means are." easiestsemsamr 'easa" a: with respect to said spindle. v

8. The device of claim 7 wherein said axial force means comprises atleast one hydraulically actuated piston which bears against one of saidbalance weights.

9. The device of claim 7 wherein said locking means and said power inputmeans are so coupled that upon actuating said weight moving means saidlocking means is in non-locking position, and when said weight movingmeans is not actuated said locking means is in locking position. 1

10. The device of claim 9 including means for sensing rotationalunbalance of said spindle.

1. A balancing device for balancing a rotating member positioned on arotatable spindle while the same is rotating about its axis of rotation,said device comprising: a. a pair of movable balance weights positionedwithin said spindle, said weights having their respective centers ofgravity radially spaced from the axis of rotation of said spindle andaxially spaced from each other, each of said movable weights being ofgenerally annular configuration and having internal gear teeth on itsinnermost surface; b. first weight moving means for moving said balanceweights relative to each other and about said axis of rotation; c.second weight moving means for moving said balance weights in unisonabout said spindle axis; and d. means for selectively engaging saidfirst or said second weight moving means whereby substantially to bringsaid rotating mass into balance.
 2. The device of claim 1 wherein saidfirst weight moving means and said second weight moving means comprisegear means meshing with said internal gear teeth to cause said balanceweights to move relative to each other when said first weight movingmeans is activated and to cause said balance weights to move in unisonabout said axis of rotation when said second weight moving means isactivated.
 3. The device of claim 2 wherein said first weight movingmeans and said second weight moving means are independently driven byseparate clutch means connected to said gear means.
 4. The device ofclaim 3 including power input means for selectively imparting rotationalmotion to each of said clutch means to thereby move said balance weightsand substantially balance said rotating member.
 5. The device of claim 4wherein said power input means comprises a clutch driving member drivenby said spindle at a predetermined speed different from that of saidspindle, said clutch driving member being selectively engageable witheach of said clutch means.
 6. The device of claim 5 including means forlocking said movable weights in any desired position relative to saidspindle.
 7. The device of claim 6 wherein said locking means comprisesaxial force means for imposing an axial force on said balance weights tofrictionally position them with respect to said spindle.
 8. The deviceof claim 7 wherein said axial force means comprises at least onehydraulically actuated piston which bears against one of said balanceweights.
 9. The device of claim 7 wherein said locking means and saidpower input means are so coupled that upon actuating said weight movingmeans said locking means is in non-locking position, and when saidweight moving means is not actuated said locking means is in lockingposition.
 10. The device of claim 9 including means for sensingrotational unbalance of said spindle.